Monopole and Dipole Antennas in a Nonlinear Isotropic Plasma

Publisher Website
Google Scholar
Abstract
The theoretical nonlinear response of a plasma is studied for the case of two RF signals simultaneously applied to the terminals of thin-wire monopole and dipole antennas of arbitrary length. Distributed nonlinear sources of charge density and current density are identified and used to calculate induced open-circuit antenna terminal voltages at harmonic, sum, difference, and intermodulation frequencies and at d.c. (rectification). The importance of the antenna as a field scatterer is identified for the calculation of radiation fields and higher-order near fields. Experiments on the terminal properties of a monopole antenna were performed in a laboratory gas discharge and quantitative agreement with cold-plasma theory is demonstrated for frequencies above about half the plasma frequency; lower frequency response closely resembles earlier predictions using warm-plasma theory. Experiments and theory for a constant RF input current indicate that the plasma frequency can be identified and therefore that the antenna system is useful for electron-density diagnostics. Experiments indicate a complex form of signal limiting or saturation, but below this level there exist situations where the nonlinear response is high enough to be classified as interference in practical systems.

This publication has 0 references indexed in Scilit: